Constant Force Balance System - Choose Weight.

New Style - Constant Force Balance System used by several Companies including Hurd, Capitol, Metal Industries, Coronet and others.
Each Coil spring has a number embossed on the side that determines the strength of the balance.
They may have one or more coils and the coils may have different numbers on each coil if used in Doubles .
Plastic Balance shoe: 1-1/4 Wide and 17/32 thick. (shade over 1/2 inch thick)
Overall Length: 2-7/8 inches prox. depending on coil size.
Number of Coils: One - If you have two coils, you're in wrong product category.
Coil Diameter: 1/2 inch wide Coil spring.
Number on Coil: Number is embossed on the side of spring.

NOTE:
Sold Each - Best if Replaced in Pairs, Should not mix old with new.
PLEASE Check all Dimensions.
Choose Coil Weight from List below.
Number Stamped on Single Coil Spring.

Sizes: 5/540, 6/640, 7/740, 8/840, and 832. 
832 is replaced with 8/840    

Priced and sold each.